Due to the need for microwave engineering, the ports of most microwave RF components are both a head, and the port of the cable connecting device is a yin yang, which cannot be directly connected to the vector network analyzer. For non-inserted devices. In actual measurements, there is a large number of non-inserted devices, and their port connection types are the same, the yin and inferior polarity is the same, and the pass-through measurement cannot be performed directly when calibration. In order to connect the non-inserted device to the vector network analyzer, the double yin or double male adapter must be added so that the test value of the vector network analyzer is not the actual value of the measurement, but the value of the adapter is added. .
The influence of the adapter is ignored in the general measurement. It is believed that the measured result is the actual value of the measurement, and the loss of the adapter and the time of time are incomplete, so that the accuracy of the measured is not obtained. . Or test different calibration methods, for example, the characteristics are not determined, and the characteristics determine the straight-up, the like, the adapter switch, the adapter removal, etc., reducing the impact of the adapter on the measurement of the measurement, but these methods regardless of the pros and cons. It is impossible to remove the impact of the adapter on the non-insert device. In this paper, the unknown characteristics of the unknown feature are tested here, according to the algorithm and hypothetical calculation value, the value of the cascade is close to the actual measurement value, thereby determining the value of the adapter, and finally being measured. Accurate value of the part, thereby removing the impact of the adapter on the test.
1 principle
The signal flow diagram (shown in Figure 1) binding scatter parameters is a simply effective method for analyzing microwave networks and microwave measurement systems. The flowchart formula also known as Mason's Non-Touching Loop Rule, referred to as Mason formula. According to the Mason formula, you can directly find the transmission value between any two points in the signal flow map.
2 verification process
There are many kinds of adapters, in order to study facilitate and universality, this test uses dual yin and double yang to verify that other types of adapter principles and processes are also the same.
In the experiment, the vector network analyzer is used (100 MHz ~ 40 GHz), 2 sets of cables, 2.4 mm calibration (AV31123, high calibration and cable, small error), programmable step 1 insensitial unit. Set linear frequency range 1 to 21 GHz, take a point per 100 MHz, the scan point 201, the intermediate frequency bandwidth 100 Hz. After the vector network analyzer two-port cable, the cable port is the calibration end face, and the cable port is the 12 system error. After the preparation is completed, use different methods for testing. In the method 1, the duplex and double male values are calculated by the 50Ω matching load; method 2, the duplex and double male values are calculated by the programmable step-by-step attenuator. The following is a detailed process of two methods.
2.1 Method 1
After the port 1 is connected to the double male joint, the rotator, short circuitry, and 50 Ω match load (as shown in Figure 2) are γao, γA, γAl, respectively. When the port 2 is connected to the double-negative connector, the circuit breaker, short circuit, 50Ω match load (as shown in Figure 3), and the measured reflection coefficients are γBO, γBs, γ BL, respectively. Then the port 1 directly adds the opening, the shorter, 50 Ω matching load, and the measured reflection coefficient is γ1O, γ1S, γ1L (as shown in FIG. 4). The port 2 is directly plus the jocker, the shorter, and the measured reflection coefficient is γ2O, γ2s, γ2L (as shown in Figure 5).
Figure 5 port 2 pick up the boot, short circuit, matched load
By the formula (2), Shuangyang, Double Yin equation [SA], [SB] is:
In the formula: M11, M12, M21, M22 are S-parameter values to be tested for the double male joint parameter value, N11, N12, N21, N22 is a dual female joint. Assuming that the network is transluitized, M12 = M21 N12 = N21, then the equation group can solve the double male S parameter matrix SA and the dual-membered S parameter matrix SB. From:
2.2 Method 2
Use a 2O db attenuator to match the load alternative 1 50 Ω matching load, and the decayer is measured by a vector network analyzer to connect the dumern, double yang reflection coefficient γal, γ BL, and the reflection coefficient of the 2O DB attenuator is γ 1L, respectively. , Γ2L. Other steps are similar to method 1. The comparison of S and the method 1 is calculated.
3 verification
For the feasibility of the above method, the calculated value of the double male bond joint is verified by two methods.
3.1 level double yang double yin
First, the S parameters of the double-yin double male stage are calculated. The S parameter of the cascaded two-port network cannot be directly calculated, and the S parameter is required to convert the S parameter to T parameters, and the cascade value [Tab] - [TA] [TB] is required, and the cascaded [Tab] is converted to [ SAB]. Double yang double-centian cascade (shown in Figure 6).
Figure 6 Shuangyang Shuangcun
The S parameter obtained by the above method is a reference value, and these values are compared to the S parameters obtained by Mason formula. All test data is processed with MATLAB software, and simulates the S-parameter graph and the S-parameter curve that is tested in the vector network analyzer.
S12, S21 can be seen from Fig. 7, and there is some difference between S11 and S22. Method 1 The two curves of the 20 DB attenuator are basically consistent in the 50 Ω matching load and method 2. The double yang double-centian cascading will follow the load, and the cascade value is set. The reason is that the 20 DB attenuator is not a standard device, and there is a reflection in Shuangyang Shuangcun stage.
Figure 7 Shuangyang Double Confucius 20 dB attenuator Calculated and Vector Network Analyzer Test S11, S22
Curve of S11 Theoretical Accounts and Vector Network Analyzer Test Curves are very close. The graph of the low frequency band, the theoretical calculation value of the S22 theory and the test curve of the vector network analyzer are consistent. The graph of the theoretical calculated value in high frequency is better because the reflection coefficient is below -40 dB and the isolation is high. In fact, the connection port of the double yang double-yin is affected. Therefore the theoretical calculated value is more than the measured value.
The standard parts, adapters, and attenuators have multiple connections in the test, and each connection will be in varying degrees. The value of the standard parts is tested by the calibration index, and there is no higher calibration system test. The measurement of the transmission parameters is indispensable to obtain the S parameter, but the experiment is only necessary to have a certain error in the results of the measurement of the reflection coefficients. There must be better results for these errors.
3.2 Programmable Stepping Decount
The following verification uses a programmable step-by-declining device, and the measurement is measured to be attenuated attenuate 0, 10 dB, 20 dB, 30 dB, 40 dB, 50 dB, 60 dB, respectively. The S-parameter of the attenuator is calculated from experimental data (as shown in Figures 8-10).
As can be seen from the above calculation: the S-parameter of the programmable step-in-negative unit that is not connected to the double male bonding is obtained is expected. The calculated value of the attenuator is verified that the transmission parameters given by Agilent are in line with the reflection parameters.
4 Conclusion
This paper is an authentication experiment that the impact of the duplex and double male adapters removal in the test of non-inserted devices. The problem of the universal adapter is specialized and simplified, but this is theoretically breakthrough on other adapters, and further research on port extension and embedding technology.
Be
Source: Wiku Electronic Market Network
Our other product:
